Avis bad experience

I hired a car from Avis Port Elizabeth at the Airport. i left R2000 as acess fee for hiring the car. When I returned the car. I was told thers a fee of R3000 that i need to pay as i axceeded my kilometres and did not fill up the fuel. i deposited funds in my fnb account and next day they took the amount that i owe them. I called them and i was told they received the cash and account is closed. to my suprise whe i woke up this morning my bank notified me that Avis tried to get funds from my account totaling to R10 000 that i have no idea what was the money about as i have paid them fully. i made a call to Avis Port Elizabeth Office asked them about the money they tried to deduct from my account, i was told that my accoubt was paid up and closed they have no idea what money was that. i am very angry with the Avis team as i trusted them with my life.